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Claude Sonnet 5.5 vs DeepSeek-V4.1-Flash-1017

Claude Sonnet 5.5 leads the LLM Stats Score 58.3 to 51.0. DeepSeek-V4.1-Flash-1017 is 7.6x cheaper per token.

Anthropic · DeepSeek · Updated for 2026

Which is better?

Claude Sonnet 5.5 leads the overall LLM Stats Score 58.3 to 51.0, ranking #2 overall.

In the 6 individual benchmarks reported for both models, Claude Sonnet 5.5 wins 4; this is a narrower head-to-head signal than the composite indexes.

On price, DeepSeek-V4.1-Flash-1017 is roughly 7.6x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

DeepSeek-V4.1-Flash-1017 also accepts a larger context window (1,048,576 input tokens), making it the stronger choice for long documents and large codebases.

Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.

Choose Claude Sonnet 5.5

  • overall performance matters — it scores 58.3 and ranks #2 on LLM Stats
  • your work emphasizes reasoning — it leads those capability indexes
  • you value its reported benchmark strengths — it wins 4 of 6 exact shared results

Choose DeepSeek-V4.1-Flash-1017

  • cost matters — it's about 7.6x cheaper per token
  • you process long inputs — it offers a 1,048,576 token context window
  • you want the most recent training data — it shipped Oct 2026
  • you need open weights you can self-host or fine-tune

At a glance

The differences that matter most.

Claude Sonnet 5.5
Anthropic
DeepSeek-V4.1-Flash-1017
DeepSeek
Core performance indexes
LLM Stats Score
58.3
#2
51.0
#15
Reasoning
57.1
#3
48.6
#18
Coding
47.5
#2
39.1
#15
Agents
43.2
#3
38.6
#9
Cost, coverage & limits
Benchmark wins
4 of 6
2 of 6
Input price
$2.00 / M
$0.30 / M
Output price
$10.00 / M
$1.20 / M
Context window
1,000,000
1,048,576

Capability indexes

Additional strengths measured across groups of related public benchmarks

4 shared
Index
Claude Sonnet 5.5
DeepSeek-V4.1-Flash-1017
Math
38.2#28
31.8#67
Vision
41.4#2
32.2#26
Tool use
35.2#2
30.9#7
Multimodal
41.1#2
35.0#14
Conservative TrueSkill rating · higher is betterHow scores work

Individual benchmarks

47 reported for Claude Sonnet 5.5 · 11 for DeepSeek-V4.1-Flash-1017

6 shared

Claude Sonnet 5.5 outperforms in 4 benchmarks (Chartography, Humanity's Last Exam (no tools, text-only), Program Bench, Terminal-Bench 4.0), while DeepSeek-V4.1-Flash-1017 is better at 2 benchmarks (AutomationBench, DeepSWE 1.1).

Claude Sonnet 5.5 shows notably better performance in the majority of benchmarks.

Mon Oct 19 2026 • llm-stats.com

Human preference

Blind head-to-head votes and playground preference scores

Pricing Analysis

Price comparison per million tokens

DeepSeek-V4.1-Flash-1017 costs less

For input processing, Claude Sonnet 5.5 ($2.00/1M tokens) is 6.7x more expensive than DeepSeek-V4.1-Flash-1017 ($0.30/1M tokens).

For output processing, Claude Sonnet 5.5 ($10.00/1M tokens) is 8.3x more expensive than DeepSeek-V4.1-Flash-1017 ($1.20/1M tokens).

In conclusion, Claude Sonnet 5.5 is more expensive than DeepSeek-V4.1-Flash-1017.*

* Using a 3:1 ratio of input to output tokens

Lowest available price from all providers
Mon Oct 19 2026 • llm-stats.com
Anthropic
Claude Sonnet 5.5
Input tokens$2.00
Output tokens$10.00
Best providerAnthropic
DeepSeek
DeepSeek-V4.1-Flash-1017
Input tokens$0.30
Output tokens$1.20
Best providerDeepSeek
Notice missing or incorrect data?

Context Window

Maximum input and output token capacity

DeepSeek-V4.1-Flash-1017 accepts 1,048,576 input tokens compared to Claude Sonnet 5.5's 1,000,000 tokens. DeepSeek-V4.1-Flash-1017 can generate longer responses up to 393,216 tokens, while Claude Sonnet 5.5 is limited to 128,000 tokens.

Anthropic
Claude Sonnet 5.5
Input1,000,000 tokens
Output128,000 tokens
DeepSeek
DeepSeek-V4.1-Flash-1017
Input1,048,576 tokens
Output393,216 tokens
Mon Oct 19 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Both Claude Sonnet 5.5 and DeepSeek-V4.1-Flash-1017 support multimodal inputs.

They are both capable of processing various types of data, offering versatility in application.

Claude Sonnet 5.5

Text
Images
Audio
Video

DeepSeek-V4.1-Flash-1017

Text
Images
Audio
Video

License

Usage and distribution terms

Claude Sonnet 5.5 is licensed under a proprietary license, while DeepSeek-V4.1-Flash-1017 uses MIT.

License differences may affect how you can use these models in commercial or open-source projects.

Claude Sonnet 5.5

Proprietary

Closed source

DeepSeek-V4.1-Flash-1017

MIT

Open weights

Release Timeline

When each model was launched

Claude Sonnet 5.5 was released on 2026-09-28, while DeepSeek-V4.1-Flash-1017 was released on 2026-10-17.

DeepSeek-V4.1-Flash-1017 is 1 month newer than Claude Sonnet 5.5.

Claude Sonnet 5.5

Sep 28, 2026

2 weeks ago

DeepSeek-V4.1-Flash-1017

Oct 17, 2026

0 days ago

2w newer

Knowledge Cutoff

When training data ends

Claude Sonnet 5.5 has a documented knowledge cutoff of 2026-06-01, while DeepSeek-V4.1-Flash-1017's cutoff date is not specified.

We can confirm Claude Sonnet 5.5's training data extends to 2026-06-01, but cannot make a direct comparison without DeepSeek-V4.1-Flash-1017's cutoff date.

Claude Sonnet 5.5

Jun 2026

DeepSeek-V4.1-Flash-1017

—

Provider Availability

Claude Sonnet 5.5 is available from Anthropic. DeepSeek-V4.1-Flash-1017 is available from DeepSeek.

Claude Sonnet 5.5

anthropic logo
Anthropic
Input Price:Input: $2.00/1MOutput Price:Output: $10.00/1M

DeepSeek-V4.1-Flash-1017

deepseek logo
DeepSeek
Input Price:Input: $0.30/1MOutput Price:Output: $1.20/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?

Judge for yourself.

Run your own prompts against Claude Sonnet 5.5 and DeepSeek-V4.1-Flash-1017 side-by-side, then vote on the output you prefer.

Claude Sonnet 5.5
✓ Preferred
DeepSeek-V4.1-Flash-1017
Open in Playground

FAQ

Common questions about Claude Sonnet 5.5 vs DeepSeek-V4.1-Flash-1017.

Which is better, Claude Sonnet 5.5 or DeepSeek-V4.1-Flash-1017?

Claude Sonnet 5.5 leads the LLM Stats Score 58.3 to 51.0. Claude Sonnet 5.5 is made by Anthropic and DeepSeek-V4.1-Flash-1017 is made by DeepSeek. The best choice depends on your use case — compare their capability indexes, individual benchmarks, pricing, and limits above.

How does Claude Sonnet 5.5 compare to DeepSeek-V4.1-Flash-1017 in benchmarks?

Claude Sonnet 5.5 scores BenchCAD (with Python tool): 96.3%, ArXivMath (with tools): 95.2%, Global-MMLU: 92.1%, MILU: 91.6%, SWE-bench Multilingual: 90.3%. DeepSeek-V4.1-Flash-1017 scores BabyVision: 92.5%, Chartography: 83.0%, DeepSWE 1.1: 77.0%, NL2Repo: 68.2%, AutomationBench: 60.5%.

Is Claude Sonnet 5.5 cheaper than DeepSeek-V4.1-Flash-1017?

DeepSeek-V4.1-Flash-1017 is 6.7x cheaper for input tokens. Claude Sonnet 5.5 costs $2.00/M input and $10.00/M output via anthropic. DeepSeek-V4.1-Flash-1017 costs $0.30/M input and $1.20/M output via deepseek.

What are the context window sizes for Claude Sonnet 5.5 and DeepSeek-V4.1-Flash-1017?

Claude Sonnet 5.5 supports 1.0M tokens and DeepSeek-V4.1-Flash-1017 supports 1.0M tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Claude Sonnet 5.5 and DeepSeek-V4.1-Flash-1017?

Key differences include LLM Stats Score (58.3 vs 51.0), context window (1.0M vs 1.0M), input pricing ($2.00 vs $0.30/M), licensing (Proprietary vs MIT). See the full comparison above for benchmark-by-benchmark results.

Who makes Claude Sonnet 5.5 and DeepSeek-V4.1-Flash-1017?

Claude Sonnet 5.5 is developed by Anthropic and DeepSeek-V4.1-Flash-1017 is developed by DeepSeek.

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